Spirit level

ABSTRACT

A spirit level has a body member containing a leveling tube, in which the base of the body member has a width greater than the width of the body member in any other plane parallel with the base. Preferably the body member is triangular in cross section and may include three elongate wing or flange members extending radially from a central hub region. The body member may have axially-extending, for example telescopic, end members.

This invention relates to spirit levels.

Spirit levels are well-known tools for use by builders and othertradesmen, whether amateur or professional, in erecting, repairing,extending and fitting out buildings or other structures, and may be usedout of doors or indoors. In use, they are placed on a working surface tocheck that it is substantially horizontal and, if necessary, to adjustthe angle of the surface to render it horizontal. However, conventionalspirit levels are prone to being easily knocked over or off the workingsurface either in windy conditions or when accidentally dislodged byanother object, since the body member which contains the levelling tubehas a relatively narrow base in relation to its height.

It is an object of the present invention to provide a spirit level whichovercomes the above disadvantages of existing spirit levels.

According to one aspect of the present invention, a spirit levelcomprises a body member containing a levelling tube, in which the baseof the body member has a width greater than the width of the body memberin any other plane parallel with the base.

Preferably, the base width is greater than the median width of the bodymember; by “median width” in this specification is meant half the sum ofthe overall base width and the top or upper width. The invention resultsin greater inherent stability in that a greater degree of lateralpivoting about a base edge is necessary before the centre of gravity isvertically above that edge.

In one embodiment, the body member is substantially triangular inoverall cross section, subject to the possibility of having rounded orchamfered linear edges. Preferably, the triangle is equilateral, wherebythe side faces of the body member may be configured to allow thelevelling tube to be viewed from any face, thus enabling any other faceof the body member to be used as the base. It will be understood,however, that the sides are not necessarily required to be planar. Thelevelling tube may be carried within the body member in conventionalmanner, either parallel with at least the base or, in the case of acurved measuring tube, with the plane which contains the curvature at aright angle to the base. The body member may comprise three elongatewing or flange members extending radially from a central hub region andthe levelling tube may be carried axially thereof with the wing orflange members being suitably cut away in a longitudinally-central zoneto allow the tube to be visible, or a levelling tube may be carried inone or preferably in each wing or flange member, parallel with thelongitudinal axis of the body member. One or more of the wing or flangemembers may also include levelling tubes disposed orthogonally to thelongitudinal axis and/or at a predetermined acute angle, conventionally45°, thereto, to enable vertical and 45° (or other angled) slopingsurfaces or workpieces to be tested. The wing or flange members may beshaped or configured to improve strength in the hub region or to providefor better contact with pipes, tubing or other curved workpiece surfaceswhile conserving the general “Y” cross-sectional shape whereby, when thedevice is placed on a flat surface, the outer regions of two of the wingor flange members provide a stable base for the body member.

In another embodiment, the spirit level may comprise a central bodymember including one or more levelling tubes, the body member havingaxially-extendable end members to facilitate use on larger surfaces. Theend members should have the same size as each other and be of generallytriangular configuration, which may include a tri-lobal configurationwith each lobe extending radially preferably with an angle of 120°subtended between each pair of lobes. The end members may be carried onarms with means for sliding, preferably axially, within the body member;the arms may be telescopic to accommodate further extension distances.The end members should have their triangular apices in registration whenviewed longitudinally with means for prevention of mutual axialrotation, for example by forming the sliding means from non-circularslidable elements. The body member itself preferably has the samecross-sectional shape and dimensions as the end members with thetriangular apices of the body member being in longitudinal registrationwith those of the end members. The end members may carry levelling tubesto enable vertical or sloping surfaces or workpieces to be tested.

Spirit levels according to the invention may be constructed from anaxially-central core member formed with recesses or cavities forreceiving keying portions of the flange members at the correctdisposition. The cavities may be dovetail-shaped in cross section forsecure accommodation of the flange members, which themselves may becross-sectionally shaped or profiled in order, for example, to provideflat workpiece-engaging surfaces whereby one such surface on one flangemember is co-planar with another such surface on another flange memberto enable the spirit level to be placed stably on a flat surfacesupported by co-planar surfaces on respective flange members.Alternatively, the flange members may be formed from sheet material to adesired cross-sectional shape and having base elements which engage inthe recesses, which may extend radially inwardly from the outer surfaceof a cylindrical core member. Preferably, the base elements of adjacentflange members are accommodated in side-by-side relationship in a commonrecess and may be retained therein by virtue of projections on eitherthe base elements or recess walls and which engage in correspondinggrooves formed in the other of the base elements and recess walls.

Embodiments of the invention will now be described by way of examplewith reference to the accompanying drawings, of which

FIG. 1 is a side elevation of one embodiment of a spirit level ofequilateral-triangular section;

FIG. 2 is a cross section through the spirit level of FIG. 1, on theline II—II;

FIG. 3 is a side elevation of another embodiment havingradially-directed wings;

FIG. 4 is a cross section on the line IV—IV of FIG. 3;

FIG. 5 is a cross-sectional view similar to that of FIG. 4 but showinganother construction;

FIG. 6 is a perspective view of an embodiment with extendible ends; and

FIG. 7 is a fragmentary cross-sectional view of an alternativeembodiment to that of FIG. 5.

Referring to FIG. 1, to a spirit level consists of a body member 11 anda levelling tube 12 containing a suitable liquid 13 forming a “bubble”of air 14 by surface tension forces, in known manner. The tube 12 hasmarks 15 formed thereon to indicate the position for the bubble when thespirit level is horizontal.

As shown more clearly in FIG. 2, the body member 11 is triangular incross section with rounded longitudinal edges; the sides 16, 17 of thebody member are cut away in a central zone 18 to enable the levellingtube to be viewed from either side. The remaining side 19 of the bodymember forms the base of the instrument and is provided with alongitudinal groove 20 to enable the instrument more easily to besupported on pipe work. However, either side 16 and 17 could be used asthe base; the levelling tube would be visible through the other of thesides 16, 17.

Referring to FIGS. 3 and 4, the spirit level has a body member 31 in thebasic cross-sectional shape of a “Y”, the three wings 32-34 beingmutually radially disposed at 120°.

The wings are faired in between adjacent pairs thereof to providearcuate seating surfaces 35-37 for use against pipes, tubes or othercurved surfaces, while the extremities 38—40 provide bases for seatingon flat surfaces as shown in FIG. 4. A central horizontal levelling tube41 is visible through cut-away parts of the fairing indicated by dashedlines 41 a and vertical and 45° levelling tubes 42, 43 are provided ateach end region, one of each in each respective wing.

In other embodiments, other cross-sectional shapes may be used; ahorizontal levelling tube could also be used in each wing in furtherembodiments.

FIG. 5 shows a cross-sectional view of another embodiment, omitting thelevelling tube or tubes for the sake of clarity. The level consistsessentially of a central cylindrical core member 45 having longitudinalgrooves or channels 46 formed in its surface and extending radiallyinwardly. The channels are dovetailed in shape, being broader across thebase than across the mouth. Each channel receives the base of aradially-disposed flange element 47 with end faces 48, 49 which convergeto form respective apices of a notional triangle (indicated by dashedlines) which encompasses the cross-sectional shape. The flanges aremechanically locked in the grooves and individual flanges may thereforebe replaced if damaged, although the flanges may be glued in place foradditional rigidity and strength. As with the embodiment of FIGS. 3 and4, the face 48 of one flange is coplanar with the face 49 of anotherflange to provide for stability on a flat surface.

FIG. 6 shows an embodiment in which a central body member 50 oftriangular tri-lobal cross sectional configuration including a levellingtube 51 in each lobe has axial telescopic tubes 52 extending from eachend carrying ti-lobal members 53 to which are attached outer telescopictubes 54 carrying outer tri-lobal members 55. The tubes 52, 54 arenon-circular, for example D-shaped, in cross section to prevent axialrotation and the lobes of the members 53, 55 are in longitudinalregistration with each other and with the lobes of the central bodymember 50. The outer tri-lobal member 55 carry further levelling tubes56. In use, the members 53, 55 may be axially extended as necessary foruse on a larger-size workpiece such as the upper surface of a masonry orbrick wall under construction.

FIG. 7 shows another construction of a cylindrical core member 57 formedwith radial channels 58 extending inwardly from the surface and disposedequi-angularly about the axis. The side walls of the channels are formedwith grooves 59. The flange elements 60 are formed from pressed sheetmetal 61; tie base portions 62 of the flanges have longitudinalprojections 63 and the base portions 62 of two adjacent flanges areaccommodated back-to-back in a common channel 58 with the projections 63engaged in the grooves 59.

1. A spirit level comprising a body member containing a leveling tube,the body member comprises a central hub region, having three radiallyelongate wing or flange members each extending radially therefrom in anequi-angular configuration, each wing or flange member providing aworkpiece-contacting surface which is co-planar with another suchsurface of either adjacent flange member, characterized in that theworkpiece contracting surface of each wing or flange member areseparated by a recess which extends longitudinally substantially theentire length of the body member, adjacent wing or flange members havingwalls which extend from an apex and subtend an angle of 120 degreesbetween them and one or more of thewing or flange members includinglevelling tubes disposed orthogonally to the longitudinal axis to enablevertical and angled surfaces or workpieces to be tested.
 2. A spiritlevel according to claim 1, in which at least one of the wing or flangemembers also includes levelling tubes disposed at an acute angle to thelongitudinal axis of the spirit level, to enable angled surfaces orworkpieces to be tested.
 3. A spirit level according to claim 1, thebody member having axially-extendable end members.
 4. A spirit levelaccording to claim 1, in which the hub region is formed with recesses orcavities for receiving keying portions of the flange members.
 5. Aspirit level according to claim 4, in which the cavities aredovetail-shaped in cross section.
 6. A spirit level according to claim4, in which the flange members are formed from sheet material to adesired cross-sectional shape and have base elements which engage in therecesses or cavities.
 7. A spirit level according to claim 6, in whichthe base elements of adjacent flange members are accommodated inside-by-side relationship in a common recess and are retained therein byvirtue of projection on either the base elements or recess walls andwhich engage in corresponding grooves formed in the other of the baseelements and recess walls.